This application claims priority to French Patent Application No. FR 01 01582 filed on Feb. 6, 2001, the entire contents of which are hereby incorporated by reference.
The present invention relates in general to improvements made to floating inflatable devices and, more specifically, although not exclusively, to those of these devices which have a large inflation volume.
Inflatable devices are inflated from a source of pressurized gas, generally consisting of one or more reservoirs or cylinders of compressed gas held on board on or in the device when the latter is self-contained.
A significant problem posed lies in the fact that the larger the size of the device, the greater its inflation volume and the more the source needs to be able to deliver a high volume of gas. This accordingly results in lengthened inflation times, something which is unacceptable when the inflatable device is an emergency device (for example a life raft) which needs to be able to be deployed as quickly as possible.
Another disadvantage due to the increase in the volume of gas needed for inflation lies in the corresponding increase in the number of gas cylinders needed for inflating the increased volumes of these large-sized devices, and therefore in the considerable increase in the weight of this equipment.
In an attempt to alleviate these last drawbacks, it would admittedly be possible to envisage the use of a gas under very high pressure which, for a given inflation volume, would allow an appreciable reduction in the number of cylinders needed, and therefore the corresponding weight. However, cylinders capable of containing a gas under very high pressure have to be mechanically very strong and, as they then have not to be excessively heavy, they have to be made of special materials. Such cylinders are therefore expensive and this solution cannot be adopted for economical reasons in the case, for example, of life preservers used at sea.
It is therefore an object of the invention to improve inflatable devices of the floating type which need to be able to be inflated on the surface of the liquid in such a way that the number of on-board cylinders intended for this inflation can be appreciably reduced in order to restrict the cost and weight of this equipment without, however, this in any way affecting the speed of inflation or the ways of packaging the device, in the deflated and folded state in a container, and without this resulting in an appreciable increase in the overall cost of the device either.
To these ends, the invention proposes a floating inflatable device which is to be able to be inflated on the surface of liquid and which for this purpose comprises inflation means including an on-board source of pressurized gas, wherein, according to the invention, said inflation means comprise a venturi supplied by said source of pressurized gas and capable of entraining ambient air which contributes to the inflating of the device, and wherein said venturi inflation means, being mounted on a wall of the said device, are protected by protective means covering them in such a way as to allow ambient air to pass freely while at the same time preventing liquid from being able to gain entry to the device to any appreciable extent.
The use of a venturi in means of inflating inflatable devices is, admittedly, already known. During inflation, the stream of pressurized gas from the source creates, at the exit of the venturi where the speed of the gas is greatly increased, a depression able to give rise to a phenomenon of ambient air being sucked in through a passage associated with the venturi. This air, entrained by the jet of gas, plays an appreciable or even predominant part in inflating the device which means that the amount of gas needed for inflating the device is greatly reduced: in this way, the desired reduction in the number of cylinders and of their weight is therefore obtained, and at the same time the rate at which the device is inflated is very appreciably increased.
However, hitherto, venturi inflation means have been used only for devices on land, or alternatively for floating devices inflated before they enter the water. By contrast, such venturi inflation means have never been employed on floating devices which are to be inflated on the surface of the liquid (the case, for example, of life rafts), because of the presence of the air passage associated with the venturi and through which the water (sea water, rain, spray) can, to a large extent, enter the interior of the device.
Furthermore, and this is a drawback which is of no lesser importance, the expansion of the gas at very high pressure during inflation is accompanied by a sharp drop in temperature leading to the formation of ice which obstructs the gas passage: inflation of the device is then interrupted. As the devices in question are, in particular, emergency devices such as life rafts, such a situation is absolutely unacceptable.
It is therefore by virtue of the additional and combined use of the protective means capable of preventing the ingress of water while at the same time allowing the circulation of ambient air that venturi inflation means can be envisaged for floating inflatable devices that need to be able to be inflated on the surface of the liquid, according to the invention.
In a preferred embodiment, it is anticipated that said protective means comprise a cowling extending over said venturi inflation means and resting on the adjacent surface of the device, and that said cowling comprises an appreciably rigid framework supporting panels respectively defining mutually offset openings and constituting at least one chicane between the outside and the venturi inflation means.
In a highly advantageous embodiment, the framework consists of pressurized inflated tubes, so that, in the situation in which the device is stored in the deflated and folded state (for example in a storage container), the framework is itself deflated and folded as is the rest of the device: this then results in no appreciable additional volume to be incorporated into the container and above all there is no rigid element likely to damage the fabric of the device.
In this case, it is advantageous for the panels to be panels of watertight fabric stretched over the framework. In a simple way, it is then possible to contrive for the panels to have a height which is shorter than that of the framework, the different thus defining said respective opening.
Also a desirable feature, the panels can be opened at least partially so as to give access to the venturi, particularly so as to allow it to be plugged at the end of inflation.
In a concrete embodiment, the framework is appreciably in the shape of a dihedron, a right-angled parallelepiped or a pyramid frustum, which leads to tubes of a simple shape which can easily inflate and which above all are simple to manufacture.
For certain applications or certain conditions of use it may be found that inflation is triggered while the device is partially or completely submerged (for example, life rafts triggered from a ship which has just gone down quickly. In order to be sure that inflation using the venturi can take place, or can at least start correctly without the ingress of water when the container is submerged, it is anticipated that the device is enclosed, in the deflated and folded state, in a watertight pouch which can be opened during inflation only when the pouch is at or above the surface of the liquid. In this case, as the inflatable device is folded up in the watertight pouch, this pouch, when inflation starts, increases in volume and drives out the water that has entered the container and thus accelerates the rising of the entity to the surface. During this phase, the venturi remains protected against any ingress of water. The container then opens only after it has reached the surface and the watertight pouch does not tear until after the container opens. During the tearing of the pouch, the means of protecting the venturi or venturis are already in place and functional.
What is more, when the device starts to inflate on the surface of the liquid, the limp fabric is level with the water surface or very slightly above it which means that the venturi, insufficiently raised, runs the risk of allowing water to enter, this being all the more true since it is necessary to wait for the entire device to have begun to take shape, and therefore to wait for a certain length of time to have elapsed, for the venturi to be raised appreciably above the water surface. To avoid this disadvantage associated with the inflation time, it is anticipated that the device comprises an interior gas-permeable buffer chamber (27) into which the venturi inflation means open, by virtue of which the buffer chamber inflates first as soon as the venturi inflation means come into operation, which means are thus raised above the liquid thereby being able to operate without the appreciable ingress of liquid. Advantageously then, the buffer chamber is equipped with at least one passage with a restriction causing the said chamber to communicate with the remainder of the interior volume of the device.
Although all the provisions of the invention can be applied to any type of floating inflatable device which needs to be able to be inflated on the surface of the liquid, a particularly advantageous application of the said provisions relates to inflatable life rafts, particularly large-sized high-capacity (for example one hundred or one hundred and fifty people) rafts which are currently under development.